Accurate measurement of <Superscript>15</Superscript>N–<Superscript>13</Superscript>C residual dipolar couplings in nucleic acids

New 3D HCN quantitative J (QJ) pulse schemes are presented for the precise and accurate measurement of one-bond ¹⁵N_1/9–¹³C₁, ¹⁵N_1/9–¹³C_6/8, and ¹⁵N_1/9–¹³C_2/4 residual dipolar couplings (RDCs) in weakly aligned nucleic acids. The methods employ ¹H–¹³C multiple quantum (MQ) coherence or TROSY-type pulse sequences for optimal resolution and sensitivity. RDCs are obtained from the intensity ratio of H₁–C₁–N_1/9 (MQ-HCN-QJ) or H_6/8–C_6/8–N_1/9 (TROSY-HCN-QJ) correlations in two interleaved 3D NMR spectra, with dephasing intervals of zero (reference spectrum) and 1/(2J_NC) (attenuated spectrum). The different types of ¹⁵N–¹³C couplings can be obtained by using either the 3D MQ-HCN-QJ or TROSY-HCN-QJ pulse scheme, with the appropriate setting of the duration of the constant-time ¹⁵N evolution period and the offset of two frequency-selective ¹³C pulses. The methods are demonstrated for a uniformly ¹³C, ¹⁵N-enriched 24-nucleotide stem-loop RNA sequence, helix-35, aligned in the magnetic field using phage Pf1. For measurements of RDCs systematic errors are found to be negligible, and experiments performed on a 1.5 mM helix-35 sample result in an estimated precision of ca. 0.07 Hz for ¹D_NC, indicating the utility of the measured RDCs in structure validation and refinement. Indeed, for a complete set of ¹⁵N_1/9–¹³C₁, ¹⁵N_1/9–¹³C_6/8, and ¹⁵N_1/9–¹³C_2/4 dipolar couplings obtained for the stem nucleotides, the measured RDCs are in excellent agreement with those predicted for an NMR structure of helix-35, refined using independently measured observables, including ¹³C–¹H, ¹³C–¹³C and ¹H–¹H dipolar couplings.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1007/s10858-005-0646-2.     

Antiradical and anti-H2O2 properties of polyphenolic compounds from an aqueous peppermint extract

Polyphenolic compounds such as eriocitrin, luteolin-7-O-rutinoside, diosmin, hesperidin, narirutin, isorhoifolin, rosmarinic and caffeic acids were identified in an aqueous extract (Ex) obtained from peppermint leaves (Menthae x piperitae folium). The content of polyphenols in Ex was as follows: eriocitrin 38%, luteolin-7-O-rutinoside 3.5%, hesperidin 2.9%, diosmin 0.8%, isorhoifolin 0.6%, narirutin 0.3%, rosmarinic acid 3.7% and caffeic acid 0.05%. The strongest antiradical activity (determined as DPPH* scavenging features) was observed for luteolin-7-O-rutinoside, eriocitrin and rosmarinic acid. Caffeic acid and hesperidin revealed a lower antiradical activity while isorhoifolin, narirutin and diosmin showed the lowest activity. The strongest anti-H2O2 activity was observed for eriocitrin, a little lower for rosmarinic acid. The rate of hydrogen peroxide scavenging activity displayed by luteolin-7-O-rutinoside and caffeic acid was lower than that of rosmarinic acids. Hesperidin appeared to be a very weak scavenger of hydrogen peroxide. Almost no anti-H2O2 activity was demonstrated for diosmin, narirutin and isorhoifolin. Among examined flavonoids, the strongest antiradical and anti-H2O2 activity was shown for compounds with two hydroxy groups bound to the Bring in ortho position in relation to each other. Replacement of one hydroxy group in the Bring with a methoxy group or removing one hydroxy group leads to decrease of antiradical and anti-H2O2 activity of flavonoids. Our results suggest that eriocitrin is a powerful peppermint antioxidant and a free radical scavenger.     

Soybean-derived phytoestrogens regulate prostaglandin secretion in endometrium during cattle estrous cycle and early pregnancy

Phytoestrogens acting as endocrine disruptors may induce various pathologies in the female reproductive tract. The purpose of this study was to determine whether phytoestrogens present in the soybean and/or their metabolites are detectable in the plasma of cows fed a diet rich in soy and whether these phytoestrogens influence reproductive efficiency and prostaglandin (PG) synthesis during the estrous cycle and early pregnancy in the bovine endometrium. In in vivo Experiment 1, we found significant levels of daidzein and genistein in the fodder and their metabolites (equol and p-ethyl-phenol) in bovine serum and urine. The mean number of artificial inseminations (AIs) and pregnancy rates in two kinds of herds, control and experimental (cows fed with soybean 2.5 kg/day), were almost double in the soy-diet herd in comparison with the control animals. In in vivo Experiment 2, three out of five heifers fed soybean (2.5 kg/day) became pregnant whereas four out of five heifers in the control group became pregnant. The concentrations of a metabolite of PGF2alpha (PGFM) were significantly higher in the blood plasma of heifers fed a diet rich in soybean than those in the control heifers throughout the first 21 days after ovulation and AI. The higher levels of PGFM were positively correlated with equol and p-ethyl phenol concentrations in the blood. In in vitro experiments, the influence of isoflavones on PG secretion in different stages of the estrous cycle was studied. Although all phytoestrogens augmented the output of both PGs throughout the estrous cycle, equol and p-ethyl-phenol preferentially stimulated PGF2alpha output. The results obtained lead to the conclusion that soy-derived phytoestrogens and their metabolites disrupt reproductive efficiency and uterus function by modulating the ratio of PGF2alpha to PGE2, which leads to high, nonphysiological production of luteolytic PGF2alpha in cattle during the estrous cycle and early pregnancy.     

Nur77 nuclear import and its NBRE-binding activity in thymic lymphoma cells are regulated by different mechanisms sensitive to FK506 or HA1004

Thymic lymphoma cells restore their sensitivity to ionomycin-induced apoptosis when treated with FK506 or HA1004. In apoptosis-resistant cells, ionomycin-induced Nur77 strongly binds DNA during the first 2 h of response, in contrast to lymphoma cells treated with ionomycin together with FK506 or HA1004, which undergo massive apoptosis. We show that Nur77 could discriminate between calcium signals sensitive to FK506 and those sensitive to HA1004, as the inhibitors differentially regulate the kinetics of Nur77 nuclear import, and FK506, unlike HA1004, inhibits Nur77 DNA-binding activity. In the presence of HA1004, NBRE binding by Nur77 protein increases with time (6 h vs 2 h), whereas the final outcome of both inhibitors is apoptosis of thymic lymphoma cells.     

Peptidoglycan amidase MepA is a LAS metallopeptidase

LAS enzymes are a group of metallopeptidases that share an active site architecture and a core folding motif and have been named according to the group members lysostaphin, D-Ala-D-Ala carboxypeptidase and sonic hedgehog. Escherichia coli MepA is a periplasmic, penicillin-insensitive murein endopeptidase that cleaves the D-alanyl-meso-2,6-diamino-pimelyl amide bond in E. coli peptidoglycan. The enzyme lacks sequence similarity with other peptidases, and is currently classified as a peptidase of unknown fold and catalytic class in all major data bases. Here, we build on our observation that two motifs, characteristic of the newly described LAS group of metallopeptidases, are conserved in MepA-type sequences. We demonstrate that recombinant E. coli MepA is sensitive to metal chelators and that mutations in the predicted Zn2+ ligands His-113, Asp-120, and His-211 inactivate the enzyme. Moreover, we present the crystal structure of MepA. The active site of the enzyme is most similar to the active sites of lysostaphin and D-Ala-D-Ala carboxypeptidase, and the fold is most closely related to the N-domain of sonic hedgehog. We conclude that MepA-type peptidases are LAS enzymes.     

Expression of Bcl-2 and Bax protein in normal pineal gland in children and young adult

Summary The Bcl family contains both pro and antiapoptotic proteins participating in the regulation of neuronal cell death in several pathological conditions. However, very little is known about physiological profiles of Bcl-2/Bax expression in normal brain. In this study, we examined expression profile of Bcl-2 and Bax proteins in normal pineal gland in children. The material for analysis was obtained by biopsy of pineal parenchyma during surgery of pineal cysts. All specimens were labeled immunohistochemically and analyzed by means of confocal laser scanning microscope. We found only few Bcl-2 expressing (0.7%) and no Bax-immunopositive (0.0%) pinealocytes. Bcl-2-positive cells were mature neurons, neither young ones nor glia.     

Synergistic Cooperation between Two ClpB Isoforms in Aggregate Reactivation

Bacterial AAA⁺ ATPase ClpB cooperates with DnaK during reactivation of aggregated proteins. The ClpB-mediated disaggregation is linked to translocation of polypeptides through the channel in the oligomeric ClpB. Two isoforms of ClpB are produced in vivo: the full-length ClpB95 and ClpB80, which does not contain the substrate-interacting N-terminal domain. The biological role of the truncated isoform ClpB80 is unknown. We found that resolubilization of aggregated proteins in Escherichia coli after heat shock and reactivation of aggregated proteins in vitro and in vivo occurred at higher rates in the presence of ClpB95 with ClpB80 than with ClpB95 or ClpB80 alone. Combined amounts of ClpB95 and ClpB80 bound to aggregated substrates were similar to the amounts of either ClpB95 or ClpB80 bound to the substrates in the absence of another isoform. The ATP hydrolysis rate of ClpB95 with ClpB80, which is linked to the rate of substrate translocation, was not higher than the rates measured for the isolated ClpB95 or ClpB80. We postulate that a reaction step that takes place after substrate binding to ClpB and precedes substrate translocation is rate-limiting during aggregate reactivation, and its efficiency is enhanced in the presence of both ClpB isoforms. Moreover, we found that ClpB95 and ClpB80 form hetero-oligomers, which are similar in size to the homo-oligomers of ClpB95 or ClpB80. Thus, the mechanism of functional cooperation of the two isoforms of ClpB may be linked to their heteroassociation. Our results suggest that the functionality of other AAA⁺ ATPases may be also optimized by interaction and synergistic cooperation of their isoforms.     

Autocrine effects of VEGF-D on endothelial cells after transduction with AD-VEGF-D

Endothelial cells in tumor vessels display unusual characteristics in terms of survival and angiogenic properties which result from the increased expression of VEGF-D and its autocrine effect. To evaluate mechanisms by which VEGF-D leads to such abnormal phenotype, we searched for proteins with modified expression in HUVECs enriched in the recombinant mature VEGF-D (VEGFD^ΔNΔC) delivered by adenovirus. Expression of membrane proteins in endothelial cells was characterized by FACS using anti-human IT-Box-135 antibodies. HUVECs transduced with Ad-VEGF-D^ΔNΔC revealed markedly increased expression of proteins involved in adhesion and migration such as (a) integrins (αVβ5, α2β1, α5β1, αMβ2, αLβ2), (b) matrix metalloproteinases (MMP-2, MMP-9, and MMP-14), (c) components of fibrinolytic system (PAI-1, u-PAR), and (d) CD45, CD98, CD147. Interestingly, there also were numerous proteins with significantly reduced expression, particularly among surface exposed membrane proteins. Thus, it can be concluded that to induce proangiogenic phenotype and facilitate migration of HUVECs, VEGF-D^ΔNΔC not only upregulates expression of proteins known to participate in the cell-matrix interactions but also silences some membrane proteins which could interfere with this process.     

Psychological view of thyroid cancer and in hyperthyroid Graves' patients - comparative exploration

INTRODUCTION: The aim of study was the evaluation of association between psychometric factors in patients with thyroid cancer and in Graves' hyperthyroid patients. MATERIAL AND METHODS: We examined 50 patients with differentiated thyroid cancer, 42 females (84.75%), 8 males aged from 32 to 64 yr. (x +/- SD: 43 +/- 8.17 yr.) and 50 hyperthyroid patients, 45 (90%) females and 5 (10%) males corresponding aged. We used the following methods: the EAS Temperament Survey (EASD) in addition for adults, EPQ Eysenck Personality Questionnaire, Polish Abbreviated Form of the MMPI (DKO-74) and Beck's Depression Scale. We compared the scores of thyroid cancer patients and hyperthyroid patients. RESULTS: We have interpreted obtained results in both groups as similarly in: mild sense depression, high emotional control, high social dependence, ambiverssion, mild level of emotional mental balance. CONCLUSION: Results of our explorations appears great psychological similarity between differentiated thyroid patients and hyperthyroid patients.     

Binding of an oxindole alkaloid from Uncaria tomentosa to amyloid protein (Abeta1-40)

The primary aim of this work was to determine the interactions of an oxindole alkaloid (mitraphylline) isolated from Uncaria tomentosa with beta-amyloid 1-40 (Abeta1-40 protein) applying the capillary electrophoresis (CE) method. Specifically the Hummel-Dreyer method and Scatchard analysis were performed to study the binding of oxindole alkaloids with Abeta1-40 protein. Prior to these studies extraction of the alkaloid of interest was carried out. Identification of the isolated alkaloid was performed by the use of thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) combined with electrospray ionization mass spectrometry (ESI-MS). The proposed approach was proved to be an efficient and accurate method for specific compound isolation and identification purposes. Moreover, analytical information from the CE approach can be considered as the valuable tool for binding constant determination. The binding constant of mitraphylline with Abeta1-40 protein determined by the Hummel-Dreyer method and Scatchard analysis equals K = 9.95 x 10(5) M(-1). The results obtained showed the significant binding of the tested compound with Abeta1-40 protein. These results are discussed and interpreted in the view of developing a strategy for identification of novel compounds of great importance in Alzheimer disease therapy.